Add swap(), empty(), and size() to result class template

3 files changed, 46 insertions, 6 deletions

diff --git a/odb/exceptions.cxx b/odb/exceptions.cxx
index b27cc37..597f40d 100644
--- a/odb/exceptions.cxx
+++ b/odb/exceptions.cxx
@@ -37,6 +37,12 @@ namespace odb
     return "object not persistent";
   }
 
+  const char* result_not_cached::
+  what () const throw ()
+  {
+    return "query result in not cached";
+  }
+
   const char* object_already_persistent::
   what () const throw ()
   {
diff --git a/odb/exceptions.hxx b/odb/exceptions.hxx
index 8c9e826..8c0fe27 100644
--- a/odb/exceptions.hxx
+++ b/odb/exceptions.hxx
@@ -50,6 +50,12 @@ namespace odb
     what () const throw ();
   };
 
+  struct LIBODB_EXPORT result_not_cached: odb::exception
+  {
+    virtual const char*
+    what () const throw ();
+  };
+
   struct LIBODB_EXPORT database_exception: odb::exception
   {
   };
diff --git a/odb/result.hxx b/odb/result.hxx
index eb7f370..9f7dcb0 100644
--- a/odb/result.hxx
+++ b/odb/result.hxx
@@ -76,6 +76,9 @@ namespace odb
     virtual void
     cache () = 0;
 
+    virtual std::size_t
+    size () = 0;
+
   protected:
     void
     current (pointer_type p)
@@ -233,6 +236,29 @@ namespace odb
       return *this;
     }
 
+    void
+    swap (result& r)
+    {
+      // @@ add swap() to shared_ptr.
+      //
+      details::shared_ptr<result_impl<T> > p (impl_);
+      impl_ = r.impl_;
+      r.impl_ = p;
+    }
+
+  public:
+    iterator
+    begin ()
+    {
+      return iterator (impl_.get ());
+    }
+
+    iterator
+    end ()
+    {
+      return iterator ();
+    }
+
     // Cache the result instead of fetching the data from the database
     // one object at a time. This is necessary if you plan on performing
     // database operations while iterating over the result.
@@ -246,16 +272,18 @@ namespace odb
     }
 
   public:
-    iterator
-    begin ()
+    bool
+    empty () const
     {
-      return iterator (impl_.get ());
+      return impl_ == 0 || impl_->end ();
     }
 
-    iterator
-    end ()
+    // Size is only known in cached results.
+    //
+    size_type
+    size () const
     {
-      return iterator ();
+      return impl_ ? impl_->size () : 0;
     }
 
   private: